Note: Descriptions are shown in the official language in which they were submitted.
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SIZING FORMULATION FOR PHENOLIC PULTRUSION
AND METHOD OF FORMING SAME
TECHNICAL FIELD AND ITTDUSTRIAL
APPLICABIL,IT~' OF THE INVENTION
The present invention relates generally to sizing formulations, and more
particularly, to sizing formulations for fiberglass reinforcement rovings
which may be used
in phenolic pultrusion. A method of malting a sizing fornmlation compatible
with
phenolic pultrusion is also provided.
BACKGROUND OF THE INVENTION
Reinforced composites are rapidly growing in popularity for. such applications
as
automobile components, boat hulls, and fishing rods. Reinforced polymeric
composites
can be formed from a polymeric matrix material, reinforcing material, or any
other desired
components in a variety of ways. Such composites are formed using glass fiber
reinforcements which provide dimensional stability and excellent mechanical
properties to
the resulting composites. For example, glass fibers provide dimensional
stability as they
do not shrink or stretch in response to changes in atmospheric conditions.
Further, glass
fibers have high tensile strength, heat resistance, moisture resistance, and
high thermal
conductivity:
Glass fibers are commonly manufactured by supplying glass in molten form to a
bushing, drawing fibers from the bushing, and then gathering the fibers into a
tow or
strand. A sizing composition, or chemical treatment, is typically applied to
the fibers after
they are drawn from the bushing. The sizing composition may protect the fibers
from
breakage during subsequent processing. Typical sizing compositions may include
coupling agents, film formers, lubricants, emulsifiers, or antistatic agents
that are dissolved
or dispersed (in the form of an emulsion or dispersion) in water. However,
some organic
solvents conventionally used, such as styrene and xylene, are flammable and
pose both a
fire and a health hazard. Lithium chloride is also commonly used in sizing
compositions
as an antistatic agent, but tends to adversely affect yield, and is therefore
undesirable for
use.
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A sizing composition is desirable if the glass is to be used as a
reinforcement for a
polymeric material. The sized strands are typically wound onto a collet,
packaged, dried,
and then wound together into a continuous roving. Several difficulties have
been
associated with the use of continuous fibers and the rovings made from these
fibers. ~ne
problem with the use of wound rovings is the breakage of the individual fibers
during
winding, unwinding, or handling of the strands. Inter-filament abrasion of the
fibers
causes them to break, and, as a result, loose ends are separated from the
fiber strands.
These loose, broken ends form a roughened layer or fuzz on the surface of the
fibers. Fuzz
may also develop when fibers break during the weaving process. This fuzz is
undesirable
because it affects the appearance of the woven product. Ereakage of the fibers
also results
in a build-up of fuzz on the contact points and other surfaces of the
processing machinery.
This fuzz buildup in tuns is exacerbated by static electricity. In addition,
the fuzz often
becomes airborne, and thus becomes a source of skin and respiratory irritation
to some
workers handling the fiber strands. Further, the fuzz may collect to form
tufts or balls of
broken fibers, which then jam the processing equipment or fall into the resin
baths used for
dipping the fiber strands.
Another problem related to the use of sizing compositions is incompatibility
between the sizing composition and the polymer matrix used to form the
composites.
Several ways to solve the problem of incompatibility between the fibers and
the polymer
composite material into which they are implanted have been attempted,
including the
development of compositions containing curing or coupling agents. However,
there
remains a recognized need for an agent that facilitates intimate bonding
between the glass
fibers and the polymer matrix.
Accordingly, a need exists in the art for an improved sizing composition which
is
easy to manufacture and apply to fibers, protects the glass fibers from
abrading, improves
the chemical interface between the resin and the glass, and does not use
include
environmentally undesirable components.
SUMMAI~~' ~F THE IIV~ENTI~1V
At least one exemplary embodiment of the present invention provides a sizing
formulation that includes 1% - 7% of a film funning polymer, 0.3°/~ -
3.5% of a silane
coupling agent, 0.5% - 3.0% of a nonionic lubricant, and 0.2% - 3.5% of a
cationic
2
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lubricant. Optionally, the sizing formulation may include 0% - 3% of a water
dispersible
aliphatic polyether based polyurethane solution. The film forming polymer
component of
the sizing composition may include any polymer identified by those of skill in
the art to
form a thin film on glass fibers. However, suitable examples of film forming
polymers for
use in the sizing formulation include resins such as acrylics, polyamides,
polyester,
polyvinyl acetate, polyurethanes, and phenolics. Cationic lubricants which can
be used in
the sizing composition include partially amidated long chain polyalkylene
imines.
Preferably, the partially amidated polyalkylene imine adduct is a condensation
reaction
product of polyethylene imine with a fatty acid such as pelargonic and
caprylic acids. The
nonionic lubricant may be a polyoxyalkylated polyalkylene glycol ester, such
as a fatty
acid monoester. Preferably, the nonionic lubricant is polyethylene glycol mono-
oleate.
Coupling agents typically used in the sizing formulation include organosilanes
such as
gamma-aminopropyltriethoxy silane, N-beta (aminoethyl) gamma-
aminopropyltrimethoxy
silane, vinyltrimethoxy silane, gamma-glycidoxypropyltrimethoxy silane,
aminofimctional
silane esters, and phenylaminopropyltrimethoxy silane.
In another exemplary embodiment of the present invention, a method for forming
a
sizing formulation that includes 1% - 7% of a film forming polymer, 0.3% -
3.5% of a
silane coupling agent, 0.5% - 3.0% of a nonionic lubricant, and 0.2% - 3.5% of
a cationic
lubricant is provided. In particular, each of the ingredients of the sizing
formulation are
separately pre-mixed in water maintained at a temperature of from
approximately 70°F -
~0°F (21.12°C-26.67°C). Preferably, the water is
demineralized water. The pre-mixes are
agitated to provide a homogeneous mixture, and then added to a main mixing
tank. The
resulting composition is then agitated in the main mixing tank for a period of
time, usually
- 10 minutes. The composition may be tested for solids content by driving off
the water
and any volatile material to yield only the solids (for example, organic
solids) present in
the mix using heat (for example, 110°F (43.33°C) for 60
minutes). Demineralized water
may then be added to attain a desired ratio of solids (for example, 3% - 6 %
solids).
DETAIZ"ED DESCRIPTION AND
PREFERRED EIvIBODIMENTS OF THE INVENTION
Class fibers used as reinforcing elements are usually coated with a size
coating
which serves to protect the fibers from damage by abrasion during processing,
handling
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and/or use, to bind the individual fibers into more-or-less tightly integrated
mufti-fiber
bundles or strands, and/or to enhance the reinforcing interaction between the
fibers and the
resinous matrix in which they are imbedded as reinforcing elements. Glass
fibers are
typically formed by flowing molten glass through a plurality of suitable
orifices (for
example, bushings) so as to attenuate these streams to the desired fiber
diameter as they
cool and solidify.
~nce the glass fibers are formed, a sizing composition is applied. Liquid
sizing
compositions can be applied by spraying, by drawing the fibers across a
suitable roll, belt,
apron, pad, etc. wet with the liquid sizing composition, or other conventional
liquid
coating methods known to those of skill in the art. The sizing composition may
be applied
to the glass fibers in-line during the formation of the glass fibers
immediately after the
fiber is formed. Application of the sizing composition in-line helps to
protect the fibers
from damage during the remainder of the forming process and subsequent
handling of the
glass fibers. Alternatively, glass fibers that were previously formed and/or
packaged may
be coated with a sizing formulation off line. The size coating on the glass
fibers reduces
the occurrence of broken filaments (fuzz) and improves processing properties
of the fibers
such as fiber bundle cohesion, fiber smoothness and softness, abrasion
resistance, and ease
of unwinding the fiber bundles. The glass fibers may then be dried (for
example, in an
oven) and collected into a suitable package for further processing, storage
and/or shipment,
such as by winding onto a continuous roving. The roving may then be used in a
subsequent process, such as a pultrusion process, to form a reinforced
composite paxt.
In a phenolic pultrusion process, a reinforced composite is formed when a
thermosetting polymer is forced between the fibers of a glass roving as it is
pulled through
a resin bath coating apparatus, profiling, and alignment dies. For example,
glass rovings
are fed into a phenolic resin bath where they are moved over spreader bars
which aid in
impregnating the resin into the glass fibers. Once these rovings axe
sufficiently
impregnated with the resin, they exit the resin bath. These impregnated
rovings are pre-
formed into a shape or profile (for example, a rod) prior to entering a
molding die. The
rovings which have the pre-formed shape are then cured into the form of the
composite by
heating continuously as the paxt passes through the heated die. The composite
part exiting
the heated die is then cut to a desired length. In this manner, the continuous
roving is
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impregnated with a polymer resin, and the resin and fibers are shaped into the
form of the
composite.
Sizing compositions for coating fibers used in such a phenolic pultrusion
process
according to embodiments of the present invention includes 1 % - 7% of a film
forming
polymer, 0.3% - 3.5°/~ of a silane coupling agent, 0.5°/~ -
3.0°/~ of a nonionic lubricant and
0.2% - 3.5% of a cationic lubricant. Optionally, the sizing formulation
includes 0% - 3%
of a water dispersible aliphatic polyether based polyurethane solution.
The film forming polymer component of the sizing composition may include any
polymer identified by those of skill in the art to form a thin film on glass
fibers. Suitable
examples of film forming polymers for use in the sizing formulation include
resins such as
acrylics, polyamides, polyester, polyvinyl acetate, polyurethanes, and
phenolics. In a
preferred embodiment, the film forming polymer is a polyamide, such as is
commercially
available from Georgia Pacific Resins, Inc., and is identified as GP 2925
(Glass and
Mineral Fiber Sizing Agent).
Cationic lubricants which can be used in the sizing composition include
partially
amidated long chain polyalkylene imines. The partially amidated polyalkylene
imines
typically have a residual amine value from about 200 to about 800 and are
reactive
products of a mixture of about CZ to about C18 fatty acids with a polyethylene
imine having
a molecular weight from about 800 to about 50,000. Amines suitable for forming
the fatty
acid salt of this reaction product include tertiary amines having a low
molecular weight,
such as, for example, where the alkyl groups attached to the nitrogen atom
(amine) have
from about 1 to 6 carbons. Preferably, the fatty acid moiety of the salt
includes from about
8 to 22 carbon atoms. Most preferably, the partially amidated polyalkylene
imine adduct is
a condensation reaction product of polyethylene imine with a fatty acid such
as pelargonic
and caprylic acids. One example of such a condensation reaction product is
commercially
available from Cognis, Inc., and is identified as Emery 6760L. Alternatively,
the partially
amidated polyalkylene imine adduct is the reaction product of tetraethylene
pentamine
reacted with pelargonic acid, tetraethylene pentamine reacted with stearic
acid, or
tetraethylene pentamine reacted with caprylic acid.
The nonionic lubricant can be a polyoxyalkylated polyalkylene glycol ester,
such as
a fatty acid monoester. Preferably, the nonionic lubricant is an alkoxylated
polyethylene
glycol fatty acid ester such as polyethylene glycol mono-oleate. In a
preferred
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embodiment, the nonionic lubricant is a mono-oleate ester including
polyethylene glycol
groups having an average molecular weight of about 400. One such particular
mono-
oleate ester that can be used is marketed commercially as PEG 400 MO by Ethox,
Inc.
The coupling agents typically used in the sizing formulation have hydrolyzable
groups that are capable of reacting with a glass surface to remove unwa~.nted
hydroxyl
groups. For example, the coupling agent can have 1 - 3 hydrolyzable functional
groups
which can interact with the surface of the glass fibers, and one or more
organic groups that
are compatible with the polymer matrix. Preferred coupling agents include
organosilanes
such as gamma-aminopropyltriethoxy silane, N-beta (aminoethyl) gamma-
aminopropyltrimethoxy silane, vinyltrimethoxy silane, gamma-
glycidoxypropyltrimethoxy
silane, aminofunctional silane esters, and phenylaminopropyltrimethoxy silane.
A
particularly suitable silane for this invention is the gamma-
aminopropyltriethoxy silane, A-
1100, which is commercially available from CK Witco Corporation.
Optionally, the sizing formulation may also include a water dispersible
aliphatic
polyether based polyurethane solution that is solvent-free, non-hazardous, and
free of
pollutants. One example of a suitable water dispersible polyether based
polyurethane
solution is HydrosizeTM U6-X03 from HydrosizeTM Technologies Inc., Raleigh,
North
Carolina.
To formulate such a sizing composition, each of the ingredients may be
separately
pre-mixed in water maintained at a temperature of from approximately
70°F - 80°F
(21.12°C-26.67°C). Preferably the water is demineralized water.
The amount of water
used for each respective pre-mix varies depending on the ease of dispersion
and solubility
of the particular ingredient. The pre-mixes can then be agitated and added to
a main
mixing tank. The resulting composition is then agitated in the main mixing
tank for a
period of time suitable to provide a homogenous solution, usually 5 - 10
minutes.
Optionally, the composition can be tested for solids content by driving off
the water and
any volatile material to yield the solids (for example, organic solids)
present in the mix
using heat (for example, 110°F (43.33°C) for 60 minutes).
Optionally, demineralized
water may be added to attain a desired ratio of solids, for example, 3% - 6%
solids. The
targeted mix solids provide the correct final strand solids.
Representative examples of sizing formulations according to the invention are
set
forth in Tables 1- 5 below.
6
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Table 1
Active Preferred Range PreferredRange
% of % % of
Material ~a~ by weight by weightof dried of dried
Solids as
received as receivedcoating coating
GP 2925 21.5 3.27 1.0 - 17.2 5-30
7.0
A-1100 58 0.72 0.3 - 10.2 5-50
3.5
Acetic 100 0.23 0.10-0.50 0
Acid
PEG 400 100 2.76 0.5 - 67.5 20-70
MO 3.0
Emery 6760L12.5 1.68 0.2 - 5.1 1-10
3.5
D.M. Water0 89.72 remainder0 0
~~ Percentage weight solids used to calculate the predicted size mix solids.
Table 2
Material % ActivePounds
Solids /
100 Gallons
GP 2925 21.5 27.20
A-1100 58 6.00
Acetic Acid 100 1.93
PEG 400 MO 100 23.00
Emery 6760L 12.5 14.00
D.M. WATER 0 760.87
Calc. Mix Solids4.09 833
Table 3
Material % ActivePounds
Solids /
100 Gallons
HydrosizeTM 30 12.55
U6-X031
GP 2925 21.5 17.51
A-1100 58 12.00
Acetic Acid 100 3.86
Emery 6760L 12.5 14.00
PEG 400 MO 100 22.00
D.M. WATER 0 751.08
Calc. Mix Solids4.59 833
HydrosizeTM U6-X03 is a water dispersible
aliphatic polyether based polyurethane solution
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Table 4
Material % ActivePounds l
Solids 100Gallons
A-11261 33.7 41.70
Acetic Acid 100 10.10
EE-7322 33 30.30
PEG 400 MO 100 13.80
D.M. WATER 0 742.9
Calc. Mix 4.54 833
Solids
A-1126 is an amino functional silane ester
2 EE732 is a modified epoxy film fornler
Table 5
Material ~ Active Pounds /
Solids 100Gallons
HydrosizeTM U6-X031 30 12.8
PD-1662 53 3.55
A-1100 58 25.97
Acetic Acid 100 8.35
Emery 6760L 12.5 4.60
PEG 400 THE MOCHmUI~I
'973 PATENT 100 17.00
D.M. WATER 0 760.73
Calc. Mix Solids 4.60 833
1 HydrosizeTM U6-X03 is a water dispersible aliphatic
polyether based polyurethane solution
2 PD- 166 is an epoxy modified polyvinyl acetate copolymer
When the sizing composition is applied to glass fibers, a roving is formed
that is
compatible with a phenolic resin bath used in a pultrusion process. The sizing
composition is highly compatible with the phenolic resin so that the
individual glass fibers
are sufficiently dispersed or wetted by the matrix resin. This promotes better
fiber strand
defilamentization, or strand breakup, which reduces fiber prominence and
improves the
uniformity or smooth appearance of the surface of the resulting composite and
promotes an
increased interface between the individual fibers and the matrix resin. This
increased
interface results in better mechanical properties, which are needed in
structural
applications. As a result, a fiber reinforced phenolic resin composite part
having superior
performance characteristics can be formed.
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In addition, the sizing composition minimizes fuzz or broken filaments in the
processing of the roving into the finished composite part, yet breaks up
during the resin
wetout process to give excellent resin impregnation. Further, improved
compatibility can
also provide for increased line speeds to improve productivity. The improved
compatibility may allow a faster cure rate which gives the manufacturer the
opportunity to
produce more material with the same equipment.
The invention of this application has been described above both generically
and
with regard to specific embodiments. Although the invention has been set forth
in what is
believed to be the preferred embodiments, a wide variety of alternatives lmown
to those of
skill in the art can be selected within the generic disclosure. The invention
is not
otherwise limited, except for the recitation of the claims set forth below.
